* The point above is that the numeric values for educ99
don’t actually correspond to years of education. For that, we need another
variable, yrsed. You can see below that yrsed gives us the actual number of
years for each category.

. table educ99, contents (mean yrsed)

----------------------------------------------------

Educational attainment, 1990 | mean(yrsed)

---------------------------------------+------------

NIU |

No school completed | 0

1st-4th grade | 2.5

5th-8th grade | 6.5

9th grade | 9

10th grade | 10

11th grade | 11

12th grade, no diploma | 12

High school graduate, or GED | 12

Some college, no degree | 14

Associate degree, occupational program | 14

Associate degree, academic program | 14

Bachelors degree | 17

Masters degree | 17

Professional degree | 17

Doctorate degree | 17

----------------------------------------------------

. *unlike educ99, yrsed has the real number of years of
education, and that allows us to do operations like take the average

*And here without weights. Is 153 a large enough sample
size to be sure that the income difference between male and female lawyers is
real? How sure are we that with a different CPS sized sample, resulting in a
different 153 male and female lawyers, that the men would earn more? That kind
of question is the one this class will be answering.